Launched in 2008, NoteHall is an online marketplace for college students who want to buy and sell class notes. Sean Conway, who has ADHD and finds it difficult to comprehend a lecture and take notes simultaneously, says the impetus to start the company came when he noticed fellow students shared his frustration. For initial funding, the founders used $70,000 they put together from Conway's inheritance and Miller's bar mitzvah money. To access documents, users purchase credits via the site's virtual currency system ($3 buys 100 credits; notes from one lecture cost 25 credits; a study guide costs 100 credits). When a student purchases credits and redeems them, NoteHall receives a commission that varies based on the product. According to Conway, 20 colleges and universities are participating now, including Drexel University and the University of Arizona, and an additional 30 will be by December. Last year, NoteHall had $40,000 in revenue, will be profitable this year, and expects to reach $900,000 in revenue in 2010.